Hello to all since this is my first post.
Im designing a modulator circuit based on an fpga chip from altera. The pins provide a 4.3v voltage output (as a logical 1) and i have a d/a selfmade circuit based on opamps (as adders). The purpose of the selfmade circuit is that by changing the resistors i can micromanage the voltage levels that it produces.
The problem is that i cant rely on the possible 4.3v output from the chip to suply the amplifiers that will create the different levels. I need a circuit that will bring the voltage to a fixed value (eg. 5 or 4v) and that will also be able to follow the data output from the chip.
For example a voltage regulator can not follow the data flow so i was thinking of using a transistor that will be suplied with fixed voltage value coming from a voltage reference circuit.
My question is:
Is there a voltage referece circuit that has the ability to provide the reference voltage when a voltage value is suplied and stop when some kind of logical zero is the input?
Also do you have another idea on how to do what i want?